Is Polk County, IA in a flood zone?
FEMA's National Risk Index puts Polk County's flood hazard at the 92.1th percentile nationally — a middling flood hazard by national standards — driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 5.1 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Mandatory flood insurance compliance in Polk County
Homes with a federally backed mortgage inside Polk County's mapped high-risk flood zone (the Special Flood Hazard Area, or SFHA) are legally required to carry an NFIP flood policy. In practice, 22.8% of them do — 366 active policies against 1,607 structures FEMA counts in that zone, leaving a real compliance gap. Across all residential structures in Polk County, not just the ones FEMA mandates, 0.4% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Polk County ranks
Polk County sits at rank 264 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 144 of 3144 by population (1 is biggest). About 516,185 people live in Polk County, Iowa, spread over 572.72 square miles.
Your street may differ from Polk County's average
670 of Polk County's 163,854 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Polk County's numbers. The guide to what the Special Flood Hazard Area actually means explains why the mandatory-insurance rule exists and who it applies to.